My problem as follows:
Ma2 = FermionSpinSum[Ma1*MaC] // ExpandAll // ReleaseHold;
Ma3 = 1/4 Contract[Ma2] /. ScalarProduct[k, k] :> 0 // ExpandAll
MIST
1/4 \[CurlyPhi](pqj,mqj).(1-\[Gamma]^5).(-\[Sigma]^(k\[CurlyEpsilon](k))).(1-\[Gamma]^5).\[CurlyPhi](-pqi,mqi) \[CurlyPhi](-pqi,mqi).(\[Gamma]^5+1).(-\[Sigma]^(k\[CurlyEpsilon]^*(k))).(\[Gamma]^5+1).\[CurlyPhi](pqj,mqj)
